* dispatcher: catch exception per every failing-message
Actually if just one message of a loaded list fails to load, an exception
is thrown and no messages of the list are added.
It's better to check if every message is valid, and if an invalid message
is found, simply skip it. (Marco Trevisan) (LP: #645512)

* twitter plugin: upgrade the "unescape" function
This function uses htmllib which is going to be deprecated; plus, if this
function was failing, sending an exception, it was blocking all the messsage
loading, since the returned message was not good (just partly
filled). (Marco Trevisan)